Modular link conveyor belts are conventionally formed as belt loops driven by power driven sprocket wheels located at one or two ends of the loop. For heavily loaded belts the power drive system dependent upon a few sprocket teeth about the sprocket wheel in driving contact with the belt modules passing over the wheel presents a series of problems. With strong sprocket teeth and powerful drive forces plastic belts wear and have short life. Also the drive forces ar not usually at the most heavily loaded portions of the belt and must transmit the drive forces through a chain of link to pivot rod couplings, thus creating tension in the belt requiring heavy duty modules. Furthermore the loading at the pivot joint accelerates wear. This type of drive system is particularly unacceptable in long belts or belts disposed in curved paths.
Conveyor belt and chain drive systems that employ a loop belt in place of a drive sprocket to drive a conveyor belt system have been proposed in the prior art for distributing driving forces over a longer conveyor belt portion and thus reducing tension in the conveyor belt. U.S. Pat. Nos. 1,939,315, Paulson, Dec. 12, 1933; 1,960,719, Stibbs, May 29, 1934; 2,405,530, Sullivan, Aug. 6, 1946; 2,868,356, Haaff, Jan. 13, 1959; and 4,058,204, Arich, Nov. 15, 1977 represent these prior art drive systems. These systems, in general, are not compatible with modular link belts having pivotable plastic links which ar subjected to significant wear and excessive belt tension in the presence of heavy or variable loading.
Also in these prior art drive systems there are many other deficiencies and limitations, particularly for universal usage with a large variety of conveyor systems employing belts of various widths, lengths and travel path configurations where drive belts require a variety of configurations. One serious deficiency in custom made complex drive belts adapted to various conveyor belt conditions is the necessity to produce and stock special drive belt links in relatively small quantities thereby significantly increasing the cost of the driving belt systems.
Conveyor belts that travel about curved paths in particular present driving problems not solved by the prior art.
A significant problem not addressed by the prior art is the compatibility of the drive belt with the conveyor belt under actual working conditions. For example if there are different dimensional changes in the modules of the respective belts in response to temperature or manufacturing tolerances, the two belts will incur incompatibility resulting in interference, power loss and increased wear.
It is accordingly an object of this invention to provide improved conveyor belt drive systems of the type that engage a modular link conveyor belt in a driving relationship by an endless loop modular driving belt extending along a significant portion of the modular link belt length, thereby to relieve tension, reduce wear and relate driving forces to load bearing portions of the conveyor belt.
A further object of the invention is to provide conveyor belt drive systems of significantly universal adaptability to belts of various lengths, widths, loadings and path configurations.
Another object of the invention is to provide plastic modular link driving belt systems for engaging a plastic modular link conveyor belt with compatible performance under working conditions.